Method of making an electric motor winding insulating barrier

ABSTRACT

An insulating barrier means and method of assembly between starting and running windings in a stator core includes insulating pegs between the windings having oppositely disposed axial projections extending beyond the outer axial ends of the stator core, and a plurality of end turn insulating separators each having a pair of transverse sections oppositely disposed at axial ends of the core interconnected by a plurality of legs disposed within predetermined stator slots and particularly between the starting and running windings adjacent to the insulating pegs with the pegs and separators overlapping for complete electrical insulation between the first and second windings. The method of construction includes the use of a coil transfer apparatus having a movable stripper which operates to simultaneously transfer the end turn insulators and the starting coils into the stator slots, preferably through the use of a plastic circular guide element.

This is a division of application Ser. No. 383,123, filed July 27, 1973now U.S. Pat. No. 3909648.

BACKGROUND OF THE INVENTION

This invention relates to a stator assembly for a dynamoelectric machinein which an insulating barrier means is placed between two or morewindings or coils.

Insulating barriers of various types have been used between starting andrunning windings in an attempt to electrically insulate one winding fromanother both within the stator slots and at the end turns. One knowntype of insulating barrier has consisted of a multiplicity of unitary,spatulate pieces of insulating material each designed for use within asingle stator slot which are alternately hand inserted from oppositeends of the stator assembly, as illustrated in U.S. Pat. No. 2,998,540.Such spatulate insulating pieces have generally contained transverseslits near the juncture of the head and shank parts.

Other known types of insulating barrier constructions between runningand starting windings have included end turn insulating separators whichprovide a pair of transverse sections oppositely disposed at axial endsof the stator assembly which are interconnected by only a pair of legs.Because of the width of the transverse sections, many of the statorslots containing both the running and starting windings have notcontained legs of the end turn separators thus necessitating theemployment of varying length insulating pegs within the slots in orderto provide complete electrical insulation, particularly at the axialends of the stator slots. Thus, longer insulating pegs have been handinserted within slots between the starting and running windings whichhave not contained legs of the end turn separators while substantiallyshorter insulating pegs were hand or machine inserted into slotscontaining such legs.

Frequently, such various types of insulating pegs used to separate therunning and starting windings differed in size and construction from theinsulating pegs used to close the stator slots and spaced adjacent tothe rotor bore which have been commonly machine inserted. Suchconstructions have necessitated the fabrication of different sizes andtypes of insulating pegs and have required costly and numerous timeconsuming steps of assembly, some of which were performed by hand.

SUMMARY OF THE INVENTION

This invention relates to a new stator construction employing aninsulating barrier construction which electrically insulates two or morecoils or windings both within the stator slots and at the axial ends ofthe stator core and further relates to a new and simplified method ofassembly.

In accordance with the invention, an insulating barrier means is placedwithin the slots containing two or more coils or windings for completeelectrical insulation between the plurality of coils both within theslots and at the end turns including the area near the axial extremitiesof the stator core assembly. Specifically, insulating pegs are placedwithin the slots containing the plurality of coils or windings toprovide the electrical separation therebetween with each peg includingoppositely disposed axial projections extending beyond the outer axialends of the stator core assembly.

A plurality of end turn insulating separators each provide a pair oftransverse sections which are oppositely disposed at the axial ends ofthe stator assembly and are interconnected by a plurality of legs whichare placed within predetermined stator slots. The end turn insulatingseparators are specially constructed so that each slot containing aplurality of coils or windings and a separating insulating peg containsone of the legs disposed between the windings adjacent to the insulatingpeg. Thus, the legs of the end turn insulators and the insulating pegscombine to electrically separate and insulate the two windings within aslot. Furthermore, the projections provided by the insulating pegs whichaxially extend beyond the stator core overlap or engage the transversesections of the end turn insulators to provide complete electricalseparation and insulation between the plurality of coils or windings,including at the area near the axial extremities of the stator coreassembly.

Preferably, the transverse sections of adjacent end turn insulators arepositioned to overlap in engaging relationship to further maintaincomplete electrical insulation between the plurality of coils orwindings at their end turns. In a further aspect of the invention, theinsulating pegs separating the windings within a slot are disposedradially outward of the legs of the end turn insulating separators.

The invention further includes a new and novel method of forming a woundstator core having a plurality of stator laminations with aligned slotscontaining two or more coils or windings which are separated orinsulated by insulating pegs and end turn insulators. Specifically, acoil transfer apparatus of the type utilizing a movable stripper, suchas illustrated in U.S. Pat. No. 3,689,976, issued on Sept. 12, 1972, andassigned to a common assignee, for example, is utilized for transferringat least one or more of the pre-wound coils into certain of the slots.In a broad aspect of the invention, the method includes the steps ofinserting the first winding or coils into predetermined ones of thewinding slots followed by the insertion of insulating pegs intopredetermined slots including the slots containing the first coils. In apreferred form of the invention, the first coils or windings and theinsulating pegs are sequentially inserted by one operation of a coiltransfer apparatus. Subsequently, the second coils are placed upon acoil transfer apparatus followed by the placing of a plurality of theend turn insulators thereon. The movable stripper is operated tosimultaneously transfer the end turn insulators and the second coilsinto predetermined ones of the slots so that each slot containing boththe first and second coils will contain an insulating peg and a portionof an end turn insulator to completely electrically insulate the pair ofcoils or windings.

The insertion of a portion of the end turn insulators within each slotcontaining both windings and located adjacent to the insulating pegspermits the use of uniformly sized insulating pegs in all slots. Suchpegs may also be utilized to close the slots to electrically insulatethe windings from the stator bore. Uniformity of dimension of theinsulating pegs made possible by the specially constructed end turninsulators also permits automatic machine insertion of the insulatingpegs thereby eliminating steps of fabrication, some of which were manualin nature.

A guide type element may be conveniently utilized in conjunction withthe coil transfer apparatus and is generally placed between the secondgroup of windings or coils and the end turn insulators when they areplaced or mounted on the coil transfer apparatus. The guide element iseffective in guiding the end turn insulators into the proper statorslots without experiencing damage or resistance due to interferenceand/or pressure caused by individual wires which make up the second coilor winding.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings furnished herewith illustrate the best mode presentlycontemplated by the inventor and clearly discloses the above advantagesand features, as well as others which will be readily understood fromthe detailed description thereof.

In the drawings:

FIG. 1 is a plan view of a stator assembly illustrating an insulatingbarrier between the end turns of the running and starting windings;

FIG. 2 is a diagramatical illustration of the stator assembly of FIG. 1showing the placement of the end turn insulators and insulating pegswithin the stator slots between the running and starting windings;

FIG. 3 is a fragmentary view in perspective showing the placement of anend turn insulator and several insulating pegs within several slots ofthe stator assembly of FIG. 1;

FIG. 4 is an elevational view showing the end turn insulator of FIG. 3;

FIG. 5 is an elevational view showing an insulating peg employed in thestator assembly of FIG. 3;

FIG. 6 is a fragmentary elevational view showing a coil transferapparatus and the placement of windings, end turn insulators and a guidethereon;

FIG. 7 is a plan view showing the guide element of FIG. 6; and

FIG. 8 is a plan view of the coil transfer apparatus of FIG. 6 showingthe placement of the end turn insulators, windings and guide elementthereon.

DESCRIPTION OF THE PREFERRED ILLUSTRATED EMBODIMENT

Referring to the drawings and particularly FIG. 1, a stator core 1 isformed from a plurality of stacked laminations 2 which are secured toprovide a plurality of circumferentially spaced and aligned windingslots 3. A two pole main or running winding 4 is mounted withinpredetermined slots 3 and provides end turns 5 at axial ends of thestator core 1. A phase or starting winding 6 is located withinpredetermined slots 3 and mounted axially inward from the main orrunning winding 4 and provides end turns 7, also at axial ends of thestator core 1. An insulating barrier 8 is placed within predeterminedslots 3 and provides an electrical separating and insulating barrierbetween the main or running windings 4 and the phase or starting winding6, as will be more clearly described hereinafter.

The stator core 1 is shown with twenty-four stator slots 3 which aredesignated S1 through S24 in FIG. 2 although other sized motors havingvarying numbers of slots may also utilize the subject invention. Eachslot 3 preferrably contains an insulating cuff 9 of conventional designwhich electrically insulates the windings within the slot from thestator core laminations 2. For purposes of clarity in illustration ofthe present invention, the main or running winding 4 is designated "R"and the starting or phase winding 6 is designated "S" in FIG. 2.

To illustrate one of many possible winding configurations for using thesubject invention, the running winding "R" in FIG. 2 is located withinthe slots S1 through S5, S8 through S17, and S20 through S24 while thestarting winding "S" is located within slots S3 through S10 and S15through S22. It is therefore evident that certain stator slots containonly one winding while other slots contain both the starting and therunning windings.

In accordance with the invention, a plurality of insulating pegs 10 arelocated within the stator slots S1 through S5, S8 through S17 and S20through S24, and insulate the running winding "R" within the slots 3. Asshown in FIG. 2, the insulating pegs 10 are utilized within the slotsS1, S2, S11 through S14, S23 and S24 which contain only the runningwinding "R" to separate and electrically insulate the winding from therotor bore 11 and to close the stator slots 3. The insulating pegs 10are also utilized within the slots S3 through S5, S8 through S10, S15through S17, and S20 through S22 which contain both the running andstarting windings, to separate and electrically insulate the runningwinding from the starting winding within the stator slots 3.

A plurality of insulating pegs 12 are located within the slots S3through S10 and S15 through S22 which contain the starting winding "S".The pegs 12 are identical in size and design to the pegs 10 and areutilized to electrically insulate and separate the starting winding "S"from the stator bore 11 and to close the stator slots 3.

A plurality of end turn insulating members 13, as shown in FIGS. 3 and4, are employed within the slots 3 for providing electrical insulationand separation between the end turns 5 and 7 of the running and startingwindings, respectively, while providing further electrical insulationbetween the two windings within the slots 3. Specifically, each end turninsulating member 13 includes a pair of spaced transverse insulatingmembers 14 and 15 which are joined by a plurality of legs 16, 17, 18 and19. The transverse sections 14 and 15 of adjacent end turn insulatingmembers 13 overlap such as illustrated at 20 to provide completecircumferential insulation between the end turns.

The legs 16 through 19 are located within certain of the slots 3 so thatthe transverse sections 14 and 15 are axially located beyond the outerextremities of the stator core 1 and are positioned between the endturns 5 and 7 to provide electrical separation and insulationtherebetween. With reference to FIG. 2, the legs 16 through 19 arepositioned within slots S3 through S6, respectively while an adjacentend turn insulator provides legs 21 through 24 within the stator slotsS7 through S10, respectively, while a third end turn insulator provideslegs 25 through 28 within stator slots S15 through S18, respectively,while a fourth end turn insulator provides legs 29 through 32 withinstator slots S19 through S22, respectively. The disclosed embodimentthus utilizes four end turn insulators 13 although it is contemplatedthat varying numbers of such specially constructed insulators could beutilized with varying sized motors.

While the total number of winding slots may differ for different sizesof motors, thus varying the number of slots containing running andstarting windings, it is important that each slot containing both arunning and a starting winding contain one leg of the end turninsulating member 13 to cooperate with the insulating pegs 10 to providecomplete electrical insulation between the windings. Specifically, theillustrated legs 16, 17, and 18 of the end turn insulator 13 are placedwithin the stator slots S3 through S5, respectively, to be adjacent tothe insulating peg 10 thereby providing further electrical insulationand separation between the running windings "R" and the startingwindings "S" as will be further described hereinafter.

An insulating peg 10 is illustrated in FIG. 5 and includes a main bodyportion 33 and a pair of oppositely disposed side walls 34 and 35 whichare flexibly connected to the main body portion 33 by folds 36 and 37,respectively. When inserted within a stator slot 3, the side walls 34and 35 of peg 10 flex to engage the opposite sides of the insulatingcuffs 9 thus surrounding a winding within a slot with electricalinsulation.

The insulating peg 10 is specially designed to have a length which isgreater than the distance between the opposite transverse portions 14and 15 of each end turn insulating member 13. Thus, the peg 10 providesopposite ends 38 and 39 which engage and overlap with the transversesections 14 and 15, respectively of the end turn insulator 13 to providea complete and uniform electrical insulating barrier 8 between the twowindings 4 and 6 both within the slots, at the end turns, and at theaxial extremities of the stator core 1. The legs 16 through 19 of theend turn insulator 13 are located radially inward and cooperate inabutting relationship with the adjacent corresponding insulating pegs 10and particularly with each main body portion 33 to provide addedreinforcement for the insulating barrier 8 and limit movement of thepegs 10 within the winding slots.

The inclusion of the legs of the end turn insulating members within eachslot containing both the running and starting windings 4 and 6eliminates the necessity of hand insertion of lengthy insulating pegswithin such slots to provide complete electrical insulation at the axialends of the stator core 1. The specially designed end turn insulatingmembers thus permits the use of uniformly sized insulating pegs 10 and12 to both electrically separate the windings within a stator slot andto enclose the stator slot from the stator bore.

Such uniformity of design of the insulating pegs 10 and 12 along withthe specially designed end turn insulating members 13 have permitted theuse of a new and novel method of fabrication utilizing a coil transferapparatus, such as shown in the patent to Donovan, U.S. Pat. No.3,689,976, issued on Sept. 12, 1972, and assigned to a common assigneeherewith. With reference to FIG. 6, a coil transfer apparatus 40includes a plurality of spaced blades 41 which correspond to the statorslots 3 into which the prewound coils are to be inserted. Thedescription of the coil transfer apparatus and its operation is found inthe U.S. Pat. No. 3,698,976 patent and further discussion thereof isdeemed unnecessary. In accordance with the method of assembly, prewoundcoils which constitute the running windings 4 are placed between certainblades 41 of the coil transfer apparatus which, in turn, are alignedwith the stator core 1 with respect to predetermined stator slots 3. Theoperation of a movable stripper carrying movable blades of the coiltransfer apparatus 40 inserts the prewound coils 4 into the appropriateslots 3 while the wedge holders of the coil transfer apparatus 40thereafter become operative to axially inject the insulating pegs 10into the stator slots 3 to provide electrical insulation for the runningwindings "R".

Following insertion of the running windings 4, the coil transferapparatus is withdrawn from the stator core 1 so that starting windings6 may be placed between certain preselected blades 41. Acircumferentially shaped disc 42 is placed within the circumferentialopening between the blades 41 of the coil transfer apparatus 40 tobecome located upon the starting windings 6 contained therein. The guidedisc 42 may optionally contain an inner circumferential opening 43 and aplurality of radial slits 44 which permit added flexibility of theguide. Subsequently, the plurality of end turn insulating members 13 areplaced upon the coil transfer apparatus 40 so that the plurality oflegs, such as 16 through 19, become located between predetermined blades41, as shown in FIG. 8. The second operation of the movable stripper ofthe coil transfer apparatus into and through the stator bore 11simultaneously inserts both the end turn insulating members 13 and thestarting winding 6 into the appropriate stator slots 3 so that each slotcontaining a starting winding also contains a leg from one of the endturn insulating members 13. When completing the insertion of thestarting winding 6, the wedge holders of the coil transfer apparatus 40again become operative to insert the insulating pegs 12 into certainslots 3 as above described to electrically insulate the starting winding6 from the stator bore 11.

The stator core assembly of the present invention which providescompletely insulated starting and running windings may conveniently beutilized in single and three phase A.C. fractional horsepower inductionmotors of the permanent split capacitor type employing a hermetic statorassembly and a squirrel cage rotor for use within compressor assembliesor the like.

It is therefore evident that the end turn insulating members 13 whichcooperate with the insulating pegs 10 within the slots between therunning and starting windings provide a highly effective and desirableinsulating barrier between the windings. After the windings, end turninsulators and insulating pegs have been inserted, the stator core andwindings may be subjected to further steps of fabrication before beingconnected to an electrical compressor or other type of operation.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims, particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:
 1. In a method of forming a wound stator core having aplurality of stacked stator laminations with aligned slots containingfirst and second coils with certain slots containing both first andsecond coils separated by insulating pegs and end turn insulators by theuse of a disc element and a coil transfer apparatus having a movablestripper operable for transferring prewound coils into said slots,wherein the steps comprise inserting said first coils into predeterminedones of said winding slots, inserting said insulating pegs intopredetermined ones of said slots including slots containing said firstcoils, placing said second coils on said coil transfer apparatus,placing said disc element upon said second coils located on said coiltransfer apparatus, placing a plurality of said end turn insulators onsaid coil transfer apparatus over said disc element, and operating saidmovable stripper of said coil transfer apparatus to simultaneouslytransfer said end turn insulators and said second coils intopredetermined ones of said slots with said disc element maintainingseparation between said second coils and said end turn insulators beingguided into said slots so that each slot containing said first andsecond coils contains at least one of said insulating pegs and a portionof said end turn insulators between said first and second coils.
 2. In amethod of forming a wound stator core having a plurality of stackedstator laminations with aligned slots containing first and second coilswith a predetermined slot containing both first and second coilsseparated by insulation means including an end turn insulator by the useof a disc element and a coil transfer apparatus having a movablestripper operable for transferring prewound coils into said slots,wherein the steps comprise placing said second coil on said coiltransfer apparatus, placing said disc element upon said second coillocated on said coil transfer apparatus, placing said end turn insulatorupon said disc element located on said coil transfer apparatus, andoperatively placing said first and second coils and said end turninsulator into said predetermined slot including operating said movablestripper of said coil transfer apparatus and simultaneously transferringsaid end turn insulator and said second coil with said disc elementmaintaining separation between said second coil and said end turninsulator being guided into said predetermined slot so that saidpredetermined slot contains a portion of said end turn insulator betweensaid first and second coils.